This past week, the frontier of blockchain development shifted to the northernmost reaches of the globe. Over 100 of Ethereum’s core contributors converged on Longyearbyen, Svalbard—a remote settlement located well above the Arctic Circle—for the Soldøgn Interop. The mission was singular and ambitious: to forge a path toward the upcoming "Glamsterdam" network upgrade. By leveraging the unique environment of the Arctic, where the sun remains visible 24 hours a day during the summer, developers engaged in a week-long, intensive "sprint" to finalize the technical architecture that will define the next chapter of Ethereum’s scaling journey.
Main Facts: The Core Objectives
The Soldøgn Interop served as the latest in a lineage of high-stakes, multi-client testing events, following the precedents set by Amphora, Edelweiss, and Nyota. Unlike broader conferences, this gathering was a single-track, hands-on engineering summit designed to "harden" the Glamsterdam upgrade.
By the close of the week, the collective had achieved three critical milestones:
- Gas Limit Calibration: Agreement on a post-Glamsterdam gas limit floor of 200 million, a substantial increase aimed at boosting network throughput.
- ePBS Maturity: Successful implementation of stable Execution-layer Proposer-Builder Separation (ePBS) running with external builders.
- Economic Finalization: Finalization of the repricing values stipulated under EIP-8037, ensuring that state-growth costs remain balanced against the increased throughput.
These accomplishments represent more than just incremental code changes; they are the architectural scaffolding required to safely scale Ethereum to meet the demands of a growing global user base.
Chronology: A Week of "Midnight Sun" Engineering
The intensity of the week was dictated by a demanding schedule. Upon arrival, the teams established a multi-client devnet environment, aiming for a 4×4 configuration (four Execution-layer and four Consensus-layer clients).
Monday and Tuesday: Establishing the Foundation
The opening days were marked by rapid debugging. Initial attempts at a 4×4 configuration encountered immediate friction, requiring a pivot to a 4×3 setup by Tuesday. This configuration provided the necessary stability for stress testing to begin in earnest. A major breakthrough occurred during a Tuesday morning Builder API breakout session, where developers simplified the specification regarding validator registration and the "bid/header/commitments" flow. This removed significant friction from the trust model governing builder payments.
Wednesday and Thursday: The Hardening Phase
Mid-week saw a focus on edge cases. A new test suite exposed a gap across all client implementations regarding execution-request invalidation. By Wednesday, teams were working late into the night, effectively utilizing the "24/7 uptime" afforded by the Arctic’s continuous daylight. Thursday morning brought a shift toward EL-side bid pathway debugging, which continued through to Friday. During this time, the teams also engaged in complex, highly technical debates regarding the future of proposer-builder interactions, specifically how to maintain resilience against P2P Sybil-based liveness attacks.
Friday: Convergence and Consensus
By the final day, the various threads of the week—ePBS, BAL (Block-Level Access Lists), and gas repricing—converged. The teams successfully stabilized the glamsterdam-devnet-2, demonstrating that the end-to-end pipeline for external builders was not only functional but robust.
Supporting Data: The Mechanics of Scaling
The decision to pursue a 200M gas limit floor is not arbitrary; it is the result of a multi-dimensional approach to network health. To understand why this is feasible, one must look at the technical components integrated during the Soldøgn week.
The Role of ePBS
Proposer-Builder Separation (ePBS) is designed to restructure how blocks are built. By introducing explicit deadlines for payload construction and reveal, the protocol gains "headroom." This allows validators more time for execution, which directly enables a higher gas limit without compromising the consensus layer’s stability.
Block-Level Access Lists (BAL)
While ePBS handles the consensus side, BALs address the execution-layer bottleneck. By providing clients with front-loaded information about a block’s read/write set, BALs enable:
- Parallel Execution: Allowing different parts of a block to be processed simultaneously.
- Batched I/O: Improving efficiency in data retrieval.
- Parallel State-Root Computation: Reducing the time required for state verification.
The BAL benchmark dashboard used during the week tracked client performance across these optimizations. By focusing on the "slowest paths" in each client implementation, the developers ensured that the 200M gas limit increase is sustainable across the entire ecosystem, not just for the most optimized implementations.
EIP-8037 and State Growth
A primary concern when raising gas limits is the potential for runaway state growth. EIP-8037 mitigates this by increasing the gas cost for state creation. During the week, developers made the pivotal decision to shift from a "dynamic" pricing model (which proved too complex to test) to a "fixed cost-per-state-byte" model. This change simplifies implementation while ensuring that as Ethereum throughput increases, the cost to store data remains economically aligned with the network’s resource usage.
Official Responses and Governance
The gathering also provided a venue for the AllCoreDevs (ACD) to refine their internal governance. In a session led by Nixo and Ansgar, the contributors discussed the "headliner" construct—the system by which major upgrades are themed. The consensus was to maintain the use of headliners but to adopt a more flexible approach, moving away from rigid EIP-to-theme requirements in favor of a "theme plus candidate EIP" model.
Furthermore, a new four-point "SFI" (Scope for Inclusion) definition was proposed to clarify how EIPs are prioritized for future devnets. This shift aims to replace the current, often bottlenecked, process with a more transparent, prioritization-ordered workflow starting with the Hegotlá upgrade. The meeting also addressed leadership transitions, with Alex Stokes announcing a three-month sabbatical, leading to a rotation of moderators across the various AllCoreDevs working groups (ACDE, ACDC, and ACDT).
Implications for the Future
The Soldøgn Interop was more than a technical exercise; it was a demonstration of the resilience and speed of the Ethereum development process. By compressing a month’s worth of asynchronous development into a single week of in-person collaboration, the core contributors proved that the current roadmap for scaling is not just theoretical—it is highly actionable.
Beyond Glamsterdam
Looking further ahead, the participants laid the groundwork for future forks. Sessions on native Account Abstraction explored how to balance complex features like batching and recovery with the hard constraints of public-mempool compatibility and statelessness. Additionally, a track on FOCIL (Fork-Choice Inclusion Lists) resulted in functional prototypes, marking the next phase of work for censorship resistance.
A New Standard for Collaboration
The choice of Svalbard as a location served as a powerful metaphor. Home to the Global Seed Vault and the Arctic World Archive, the region is dedicated to the long-term preservation of human knowledge. By including a snapshot of the Ethereum source code in these facilities, the community is signaling that they view the protocol not just as software, but as a critical piece of global digital infrastructure.
The "midnight sun" that enabled the developers to work around the clock reflects the 24/7 nature of the Ethereum network itself. As the contributors return home, the focus shifts from prototyping to production-readiness. The code written in the cold, bright light of the Arctic will now undergo rigorous testing, with the final parameters for the 200M gas limit set to be debated and finalized on upcoming public AllCoreDevs calls.
Ultimately, the Soldøgn Interop has successfully de-risked the Glamsterdam upgrade, ensuring that when the network does scale, it does so with the collective wisdom, testing, and consensus of the entire global developer community. The success of the week serves as a testament to the power of human coordination in the pursuit of a decentralized, scalable, and resilient future for the internet of value.
